1. Field of the Invention
The present invention to an image correcting apparatus and method in an imaging device.
2. Description of the Related Art
Generally, when a user captures an image of a subject, handshaking occurs, and a digital imaging device, such as a camera, may be shaken due to handshaking. Such shaking causes an image input through an image sensor to be shaken to result in a degradation of quality of an imaging outcome.
Recently, cameras have becoming smaller and lighter, and thus, handshaking intensifies, and as imaging is increasingly performed while on the move, solution to the problem of shake holds a place as an important factor to obtain quality images.
A digital imaging device may have a handshake correction function to prevent failure of imaging due to handshaking, and a technique of automatically correcting handshaking by a camera is known as an optical image stabilizer (OIS).
In general, while a certain image being captured by using a camera, movements such as shaking of a hand or body, a movement of a hand or a body, and the like, may be delivered to the camera, and the captured image is blurred, rather than being clear (or sharp), due to the delivered movement.
In general, there are two types of camera movement.
A first type of camera movement is a vertical camera movement on a lens axis thereof (or an axis of an image sensor), and a second type of camera movement is a horizontal camera movement on a lens axis. A vertical movement is called pitching, and a horizontal movement is called yawing. Each time a user captures an image by pressing a shutter button of a camera, the pitching or yawing movement of the camera occurs.
In order to correct such a camera movement, an optical image stabilizer (OIS) scheme, one of typical conventional arts, is provided.
The OIS scheme includes two types of scheme: an image sensor shift scheme and a lens shift scheme. Portable imaging devices commonly use the image sensor shift scheme. In the image sensor shift scheme, an image sensor is moved, while following a movement of an image generated according to handshaking. Namely, the image sensor is moved in the opposite to a direction of handshaking to allow an image focused on the image sensor to be constantly maintained in position. The lens shift scheme is a scheme in which a lens, instead of an image sensor, is moved.
The related OIS scheme has the following limitations.
In case of capturing a still image, when a surrounding environment is dark, an exposure time may be adjusted to be lengthened, and in this case, if displacement of handshaking is at an angle equal to or greater than a correction angle of an OIS module even for a short time during a long period of time, an image is blurred. The correction angle refers to a range in which a clear image (or a sharp image) is captured when a degree of shake occurring in the event of image capturing is converted into an angle. As the correction angle is greater, great shake may be correct.
For example, in relation to a correction angle of an OIS module, a specified product guarantees a correction angle of approximately 1 degree. The limitation in the correction angle has some reasons.
First, displacement of a lens shift in an OIS module is very small. This is because an OIS module itself has a limitation in size. Also, this is associated with performance of an actuator.
Second, an operation range of a motion sensor within an OSI module to measure handshaking is very narrow. In case of a movement by 1 degree or more, it falls outside of the operation range of the motion sensor, rendering an output of the motion sensor to be saturated. In case of a motion sensor, an operation range thereof is a trade-off with resolution, so a motion sensor is designed according to OIS module performance.
U.S. Pat. No. 8,373,761 is an example of conventional art, which describes a shake correcting method and apparatus thereof in a digital imaging device, whereby a shake of a digital imaging device is corrected by driving an optical shake correcting member and a shake (or a movement) of a subject is corrected by the optical shake correcting member or a digital image stabilizing unit upon translating information of the subject that comes to an image capture surface in real time, thereby capturing a subjected-centered stabilized image. However, when an exposure duration lengthens, the shake correcting method and apparatus described in U.S. Pat. No. 8,373,761 lack the ability to prevent generation of blur in an image in a case in which displacement of handshaking is at an angle equal to or greater than a correction angle of an OIS module even for a short time during a long period of time.
Thus, an image correcting apparatus and method in an imaging device that may be capable of obtaining a clear image by preventing generation of blur in an image when displacement of handshaking is at an angle equal to or greater than a correction angle of an OIS module are required.